Depicted in FIG. 1 is an idealized MIMO operation scenario with two pairs of user groups communicating between desired terminals independently and concurrently via a common frequency slot without mutual interferences. It would be nice to have total 3× frequency re-use of the allocated frequency slot; 2× for sending Sa and Sb from Atx to Arx while 1× for transmitting Sc stream from Btx to Brx. In the real world, techniques of MIMO are used to minimize mutual interferences by taking advantages of multiple paths in the 3 communication channels.
The scenario may be expanded to more than two communicating groups, several of them might be communicating simultaneously. Distributed MIMO systems usually addressed capacity in benign scenarios and are generally limited to closed, narrowly focused systems, and do not address the complexity of radios automatically negotiating collaboration groups and roles or the advanced signal processing to suppress interference and increase energy to a particular location in order to maximize the link characteristics. Further, existing work does not show how different groups can optimally communicate given this information.